Write each generated character property lisp file only once

Write each generated character property lisp file only once

* admin/unidata/unidata-gen.el (unidata-file-alist):
Rename from unidata-prop-alist.  All users changed.
Use file name rather than property name as the key.
(unidata-prop-prop): New function.
(unidata-prop-index, unidata-prop-generator, unidata-prop-docstring)
(unidata-prop-describer, unidata-prop-default, unidata-prop-val-list):
Change to parse the argument rather than unidata-prop-alist.
(unidata-gen-table-character, unidata-gen-table)
(unidata-gen-table-symbol, unidata-gen-table-integer)
(unidata-gen-table-numeric, unidata-gen-table-word-list)
(unidata-gen-table-name, unidata-gen-table-decomposition)
(unidata-gen-table-special-casing): Pass index as an argument.
(unidata-check): Adapt to unidata-file-alist.
Pass index to generator functions.
(unidata-gen-files): Adapt to unidata-file-alist.
Write each output file once only.  Overwrite rather than delete.